The invention relates to secure communication over a link.
Television programming and associated data may be broadcast over a number of different transport media, which may include cable networks, digital satellite television links, and other wired or wireless links. Paid television broadcasts, in which consumers pay for specific programs or channels that they would like to view (e.g., movie channels, pay-per-view programs, etc.), have become increasingly popular. To provide pay television services, conditional access systems have been used by broadcasters to enable viewing of such paid television broadcasts by authorized viewers.
In conditional access systems, broadcast programming content is typically encrypted according to some conditional access cryptographic protocol. In addition, an authorization process typically is performed to enable receipt of encrypted content by authorized receivers. The authorization process may include sending instructions to each of a potentially large population of addressable receivers (such as those located in set-top boxes, for example).
Authorization may be performed by sending an authorization signal that is targeted, or addressed, to a receiver along with the encrypted content. The authorization signal enables the addressed receiver to decrypt the encrypted content according to a conditional access protocol so that a clean copy of the programming content may be produced for viewing.
However, the encrypted information transmitted in a conditional access system may be circumvented relatively easily by unauthorized descramblers. Such unauthorized access causes loss of revenue to service providers as well as degradation of transmitted signals due to extra unexpected loading. Thus a need exists for an improved protection scheme for broadcast signals or other transmitted information.
In general, according to one embodiment, a method of protecting communications in a receiver having a first and a second module includes issuing a request to a transmitter. The identities of the first and second modules are verified based on information in the request. The transmitter transmits a predetermined message to the receiver after verification. The first and second devices are authenticated based on the predetermined message.
Other features and embodiments will become apparent from the following description and from the claims.